After almost a year after presentation of INR21700-48G (High Energy 4800mAh cells in new 21700 format) they seems to be finally available on the retail market. I recently found them listed by Fasttech and IMR Bateries. I have already ordered few samples for some tests

I have ordered 4pack from Fasttech with total price of 36,81USD includung "free" shiping to EU (shipping costs in checkout costs another 1,7USD). Also they do not have them already on stock, they promise shipping in 7 business days. I am trying to get these cells for almost whole a year. They have them on stock on AkkuTeile in Germany but the price of 4 cells with shipping cost is 52,7Eur so I chose Fasstech and hope taht they will resupply them early

And there are first power and capacity test: https://www.e-cigarette-forum.com/forum ... 0b.825429/ They confirms it is a High Energy structure cells as expected. So this cell is good for EVs and ESS with up to common 0,5C average power with only some short peaks. Also interesting is that this cell have lower standard charge rate of 0,3C than today most common 0,5C.

I'm working on getting 40 of the 48G cells and 40 of the Sanyo INR21700 5000mah cells to mess with. I know this form factor is 100% bleeding edge right now, but I think it's going to make 18650's much cheaper. The charge densities and discharge rates will be in the new 21700's and the 18650 will have to get cheaper to compete since it won't be able to compete on capacity or discharge rates in a very short time frame. Give it a year and I bet you see 30Q's dropping by a dollar each.

I've purchased 40 Samsung INR21700-48G. They have 2C discharge. According to the spec sheet this reduces their life span...whatever that means since it's not specific. At 5000mah and 1C, paralleling them will still result in good current supply. My blue scooter runs on used laptop cells scrounged from laptop battery packs. It's a 12P pack and assuming 2600mah that's 30 amps and I typically run at 2C max. The cells have never gotten warm from use. I bet 6-8 cells of the INR's in parallel will keep current load sufficiently low to not be a problem.

I'm making my decisions based on capacity per cell instead of discharge rates. I can plan around capacity or discharge rates easily enough either way.

Does anyone have any form of 21700's yet in their hands? What's your opinions so far?

Last edited by ElectricGod on Dec 13, 2017 4:36 pm, edited 1 time in total.

1. The cells pack together a bit better than 18650's. This means more total capacity in the same amount of space.
2. The greater cell capacity was significant. I've been using 18650's and LIPO for a good while and really wanted a cell that would have lots of capacity per cell that wasn't LIPO.

To date, I have been testing on my SkyRC D100 charger and a 6S 21700 battery holder I made.

Cell specs say full charge at 4.2 volts and discharged at 2.5 volts. Everything I've ever known about LION before says fully charged is 4.1 volts and discharged at 2.75 volts. Did something change that I'm not aware of?

I tested the cells soon after their arrival and they were all at 3.58 volts. I then charged them to full (4.1 volts) and recorded their capacities. All cells came in at around 3400 mah. Some had a bit more capacity.

My SkyRC D100 charger doesn't go lower than 2.9 volts and these cells are rated down to 2.5 volts. I'm not really testing them to full capacity when I do a discharge test. My results so far are a bit skewed as a result since I'm not going down to 2.5 volts or up to 4.2 volts. So far I see 3600mah down to 2.9 volts. They are rated at 4800mah so that means that between 2.5 volts and 2.9 volts and above 4.1 volts is another 1200mah that so far I am not measuring. I'm skeptical, but we will see. My next round of testing will be at 4.2 volts.

My experience with any battery pack is that the closer to discharged you get the more sag you experience. My expectation is that these cells at below 2.9 volts are going to sag a good bit. My D100 discharges at 400mA which is not a load test, just a capacity test. I have 35 halogen bulbs I've used for load testing many times. Each bulb is 12v, 55w, 4.6 amps. 2 of these bulbs in series will be pretty close to a 1C load on the 6S pack. I'll put a watt meter in between the pack and the load to measure Ah and a cell monitor on the balance lead to measure individual cells.

I have checked 12-15 cells to determine their Ir. Most are in the 35-38 milli ohm range and a few as high as 43 milli ohms. This seems somewhat disappointing, but everything I've read elsewhere shows this is a typical Ir for this cell. However, it may be that these cells don't increase their Ir like most cells do as they age. In that case 35-38 milli ohms isn't that bad. Very rarely do people scrutinize their packs individual cells after they are 6 months old or older. It is common for cells to creep up to 40 milli ohms or higher in that time frame.

Future LION development is coming. Supposedly 6000mah capacity in the 21700 is coming soon. Maybe wait until we see capacities over 5000mah before buying? I ran into a deal on what are supposedly Samsung cells rewrapped to be generic and are rated at 5000mah. I didn't buy them. If Samsung won't at least put their name on the wrapper, why should I trust them?

I'm charging to 4.2 volts now and seeing 4700mah capacity. My charger is still running down to 2.9 volts. That may be close enough to 4800mah for my purposes. I will next try them loaded at 4.2 volts and down to 2.5 volts. Right now I'm charging all cells to 4.2 volts.

Nice results. My samples of Samsung INR27100-48G cells, ready for cycle life test, are still laying on the table because I do not have any test channel free. Tesla and Boston cells gets the priority. But I am waiting for another 16 test channels till the end of January.

Nice results. My samples of Samsung INR27100-48G cells, ready for cycle life test, are still laying on the table because I do not have any test channel free. Tesla and Boston cells gets the priority. But I am waiting for another 16 test channels till the end of January.

I'd like to see how you are testing. Post pics please!

I'm currently charging all the cells so I can start load testing down to 2.5 volts.

1. The cells pack together a bit better than 18650's. This means more total capacity in the same amount of space.

. They are rated at 4800mah so that means that between 2.5 volts and 2.9 volts and above 4.1 volts is another 1200mah that so far I am not measuring. I'm skeptical, but we will see. My next round of testing will be at 4.2 volts.

The bigger diameter makes no difference to the % packing for any given area.
Its highly unlikely a cell will have an extra 33% capacity between 2.5-2.9 and 4.1-4.2 volts.
I suggest you review your test proceedure and compare it to Samsungs specifications and test methods.
Most cells are capacity tested at a discharge rate of 0.2C

1. The cells pack together a bit better than 18650's. This means more total capacity in the same amount of space.

. They are rated at 4800mah so that means that between 2.5 volts and 2.9 volts and above 4.1 volts is another 1200mah that so far I am not measuring. I'm skeptical, but we will see. My next round of testing will be at 4.2 volts.

The bigger diameter makes no difference to the % packing for any given area.
Its highly unlikely a cell will have an extra 33% capacity between 2.5-2.9 and 4.1-4.2 volts.
I suggest you review your test proceedure and compare it to Samsungs specifications and test methods.
Most cells are capacity tested at a discharge rate of 0.2C

For that "test", my RC charger was set to charge to 4.2 volts and to discharge down to 2.9 volts. I then charged to 4.2 volts and used it's discharge function to run those cells down. I tested 36 cells in sets of 6 cells. It has a windows app so you can watch the actual charging and discharging graphs of any particular set of cells. All I had to do is let the RC charger run and then record it's end results. My results are as I have stated straight from the RC charger. So no "mis-testing" was done. The results are what they are. I was discharging at 400 ma which is a little lower than .2C or .14C

The only explanation that makes sense and accounts for the additional capacity is in this little extra bit of voltage between 2.5-2.9 and 4.1-4.2 volts. Otherwise, if I discharge from 4.1 volts down to 3 volts, I see my previous capacity results or 3400mah from the exact same charger and discharge set up.